线程基础

多线程基础(源于马士兵教育课程)

1.什么是线程

package com.mashibing.juc.c_000;
import java.util.concurrent.TimeUnit;
public class T01_WhatIsThread {
    private static class T1 extends Thread {
        @Override
        public void run() {
           for(int i=0; i<10; i++) {
               try {
                   TimeUnit.MICROSECONDS.sleep(1);
               } catch (InterruptedException e) {
                   e.printStackTrace();
               }
               System.out.println("T1");
           }
        }
    }
    public static void main(String[] args) {
        //new T1().run();
        new T1().start();
        for(int i=0; i<10; i++) {
            try {
                TimeUnit.MICROSECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("main");
        }

    }
}

• new T1().run();函数的简单调用,先执行输出10个T1,后输出10个main
• new T1().start();开启一个新的线程,T1,main交替输出

2.如何创建线程

package com.mashibing.juc.c_000;
public class T02_HowToCreateThread {
    static class MyThread extends Thread {
        @Override
        public void run() {
            System.out.println("Hello MyThread!");
        }
    }
    static class MyRun implements Runnable {
        @Override
        public void run() {
            System.out.println("Hello MyRun!");
        }
    }
    public static void main(String[] args) {
        new MyThread().start();
        new Thread(new MyRun()).start();
        new Thread(()->{
            System.out.println("Hello Lambda!");
        }).start();
    }
}
//请你告诉我启动线程的三种方式 1：Thread 2: Runnable 3:Executors.newCachedThrad

• 继承Thread,重写run()方法
• 实现Runnable接口,将对象作为参数传入new Thread()对象构造函数中
• Thread对象中传入lambda表达式

3.sleep,yield,join

package com.mashibing.juc.c_000;

public class T03_Sleep_Yield_Join {
    public static void main(String[] args) {
//        testSleep();
//        testYield();
        testJoin();
    }
    static void testSleep() {
        new Thread(()->{
            for(int i=0; i<100; i++) {
                System.out.println("A" + i);
                try {
                    Thread.sleep(500);
                    //TimeUnit.Milliseconds.sleep(500)
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
    static void testYield() {
        new Thread(()->{
            for(int i=0; i<100; i++) {
                System.out.println("A" + i);
                if(i%10 == 0) Thread.yield();


            }
        }).start();
        new Thread(()->{
            for(int i=0; i<100; i++) {
                System.out.println("------------B" + i);
                if(i%10 == 0) Thread.yield();
            }
        }).start();
    }
    static void testJoin() {
        Thread t1 = new Thread(()->{
            for(int i=0; i<100; i++) {
                System.out.println("A" + i);
                try {
                    Thread.sleep(500);
                    //TimeUnit.Milliseconds.sleep(500)
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
        Thread t2 = new Thread(()->{

            try {
                t1.join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            for(int i=0; i<100; i++) {
                System.out.println("A" + i);
                try {
                    Thread.sleep(500);
                    //TimeUnit.Milliseconds.sleep(500)
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });

        t1.start();
        t2.start();
    }
}

• sleep,当前线程睡去,其他线程执行
• yield,当前线程谦让的退出一下,进入等待队列等待执行
• join,等待join的线程执行完才能继续执行,用于实现线程A需在线程B后执行这类要求

4.线程状态

package com.mashibing.juc.c_000;
public class T04_ThreadState {
    static class MyThread extends Thread {
        @Override
        public void run() {
            System.out.println(this.getState());
            for(int i=0; i<10; i++) {
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(i);
            }
        }
    }
    public static void main(String[] args) {
        Thread t = new MyThread();
        System.out.println(t.getState());
        t.start();
        try {
            t.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(t.getState());
    }
}